/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.tomcat.util.http.parser;

import org.apache.tomcat.util.collections.ConcurrentCache;

import java.io.IOException;
import java.io.StringReader;

/**
 * Caches the results of parsing content-type headers.
 */
public class MediaTypeCache {

	private final ConcurrentCache<String, String[]> cache;

	public MediaTypeCache(int size) {
		cache = new ConcurrentCache<String, String[]>(size);
	}

	/**
	 * Looks in the cache and returns the cached value if one is present. If no
	 * match exists in the cache, a new parser is created, the input parsed and
	 * the results placed in the cache and returned to the user.
	 *
	 * @param input The content-type header value to parse
	 * @return The results are provided as a two element String array. The
	 * first element is the media type less the charset and
	 * the second element is the charset
	 */
	public String[] parse(String input) {
		String[] result = cache.get(input);

		if (result != null) {
			return result;
		}

		MediaType m = null;
		try {
			m = HttpParser.parseMediaType(new StringReader(input));
		} catch (IOException e) {
			// Ignore - return null
		}
		if (m != null) {
			result = new String[]{m.toStringNoCharset(), m.getCharset()};
			cache.put(input, result);
		}

		return result;
	}
}
